1. Field of the Invention
The present invention relates to a selective call receiver, and in particular to a selective call receiver for use with a portable data processing apparatus.
2. Description of the Related Art
FIG. 10 shows a conventional selective call receiver 100, hereinafter referred to simply as the receiver 100, commonly called a pager, which is in widespread use. The receiver 100 is small and light, and thus can easily be carried in a pocket, an attache case, a handbag, etc.
The receiver 100 receives a radio signal transmitted from a base station (not shown). The radio signal includes synchronizing information, calling information, and message information. The receiver 100 searches for the synchronizing information, and decodes the calling information and the message information when it detects the synchronizing information.
If the decoded calling information coincides with calling information assigned to the receiver 100 which is stored in the receiver 100, the receiver 100 stores the decoded message information and displays it on a display 102.
The receiver 100 is powered by a primary battery 101 such as a zinc-silver oxide battery, a zinc-air battery, etc. The primary battery 101 must be replaced about once a month.
Replacing the primary battery 101 of the receiver 100 every month or so is inconvenient, and therefore it would be advantageous to use a secondary battery, commonly called a rechargeable battery, instead of the primary battery 101 to power the receiver 100.
However, if a rechargeable battery were to be used to power the receiver 100, it would be necessary to provide the receiver 100 with a charging circuit for charging the rechargeable battery, and a connector for connecting the charging circuit to an AC/DC converter for converting AC power from a commercial power source into DC power for use by the charging circuit.
One new use for the receiver 100 which has recently been developed is to connect the receiver 100 to a portable data processing apparatus, such as a portable personal computer, to enable the portable data processing apparatus to display and process message information received by the receiver 100. One example of a portable personal computer is a notebook computer which can perform word processing, document storage, and other data processing operations.
The portable data processing apparatus is powered by a battery or an AC power supply both having a much higher power capacity than the battery which powers the receiver 100. If it were possible to power the receiver 100 with a rechargeable battery and to charge the rechargeable battery with power from the battery or the AC power supply of the portable data processing apparatus, the receiver 100 would be easier and more convenient to use.